Conventional internal combustion engines are provided with an intake manifold through which combustion air is supplied to the engine. Conventional engines are also provided with a separate fuel rail through which fuel is supplied to the individual cylinders. The provision of separate elements not only increases the manufacturing expense for the individual parts, but also the assembly costs because two separate elements must be individually mounted to the engine. In addition, the provision of two separate parts increases the overall weight of the engine.
The present invention provides a combined or integrated air intake manifold and fuel rail for an internal combustion engine. The device of the invention has the specific advantages of lower manufacturing costs because only a single part needs to be produced, lower assembly costs because only a single part needs to be attached to the engine during assembly, and lower overall weight. In addition, the sealing of the intake manifold and fuel supply is simplified because a single seal can be used for both elements. The invention comprises a molded intake manifold body which defines an air channel for supplying combustion air to air intake ports of individual cylinders of an internal combustion engine. The manifold body is provided with mounting flanges by which it is secured to the head of an engine by mounting bolts. In the mounting face of one of the flanges of the intake manifold, an elongated recess is formed. This recess is arranged to register with fuel delivery holes in the engine head which lead to fuel injectors for the individual cylinders. The intake manifold is mounted with the mating surfaces of the flanges against a surface of the engine head. One of the mounting flanges of the intake manifold is disposed so that it covers an array of individual fuel delivery holes, which in turn lead to fuel injectors for the individual cylinders. When the intake manifold is mounted against the mounting surface on the engine head, the recess in the mounting surface on the manifold and the mounting surface of the head together form a closed channel which serves as a fuel delivery channel. Fuel is supplied to the recess in the bottom of the intake manifold flange for distribution through the fuel delivery holes to the individual fuel injectors. The fuel supply may be accomplished by connecting a fuel line leading from a fuel pump to a connecting stem on the intake manifold. The connecting stem is preferably provided on its outer diameter with annular ribs which serve to hold the fuel line on the stem. A bore is formed through the center of the stem and extended through the manifold flange until it opens into the aforementioned recess in the mounting surface of the intake manifold.
If the intake manifold is made of a material with sufficient plasticity or resilience, it may be self sealing against the engine head. Alternatively, however, a separate seal member may be provided between the intake manifold and the engine head. If desired, recesses may be formed in the mating surface of the intake manifold to accommodate such seals.
The integrated intake manifold and fuel rail of the present invention may be manufactured by any suitable method. For example, it could be machined from a solid block of material. It is preferred, however, for economic reasons to form the integrated intake manifold and fuel rail by casting or molding. The manifold may be made of any suitable material such as metals, e.g., cast iron, aluminum or titanium, or synthetic resins, e.g., polyamides such as nigh strength nylon 6 or nylon 6-6 polymers.